Electrochemical cells produce electricity through a chemical reaction. Primary cells are single use cells, and must be discarded once the chemical reaction therein has progressed to a point at which meaningful electricity cannot be produced. Thus, using primary cells requires a source of additional primary cells. Secondary cells can be recharged by connecting the anode and cathode to a source of electricity, and can therefore be used multiple times. However, re-using a secondary cell requires access to a source of electricity for recharging the cell. Individuals in “off-grid” locations may not have access to either additional primary cells or a source of electricity for recharging secondary cells. Additionally, purchasing electrochemical cells and/or recharging equipment may not be within the means of people in less wealthy locations. Alternatively, individuals may be temporarily located off-grid, and/or be located in locations with some limited access to electricity, and such individuals may have a need to store electricity for those times when they do not have access to a source of electricity. It is helpful for such individuals to be able to construct a useful battery from materials that can be easily acquired in their location.
Numerous examples of electrochemical cells have been proposed, with several examples being described below. The entire disclosure of each and every reference identified herein is expressly incorporated herein by reference.
An example of a presently proposed electrochemical cell is WO 2017/035257, which discloses in all iron redox flow battery tailored for off grid portable applications. The battery is made from a low-carbon steel negative electrode (anode), a paper separator, a porous carbon paper positive electrode (cathode), and an electrolyte solution containing 0.5 M Fe2(SO4)3 active material and 1.2 M NaCl supporting electrolyte. The cell is intended to be recharged by replacing the active materials periodically, rather than charging with an external electrical supply. The active ingredient may alternatively be FeCl3, and the concentration of either active material may range from 0.2 5 M to 2 M. The membrane can be either AMX, Duramic, or printer paper. Na2SO4 can be used instead of NaCl.
US 2017/038508 discloses a cerium-hydrogen redox flow cell. The positive electrode is single woven platinum, expanded platinized Nb, or expanded platinized Ti mesh. The negative electrode is also platinum, such as platinum on carbon. The electrolyte is an aqueous solution of cerium methanesulfonate and methanesolfonate acid, and this is fed from a storage tank to the positive electrode. Gaseous hydrogen is fed from a storage tank to the negative electrode.
U.S. Pat. No. 9,413,025 disclose a hybrid flow battery with a manganese based anolyte and catholyte. The electrolyte includes (NH4)2SO4, NH4HSO4, and mixtures thereof. The electrolyte system may also include a second supporting electrolyte, which is H2SO4. One example includes about 1 M to about 2 M (NH4)2SO4 in about 1 M H2SO4, and also includes about 1.18 M manganese salt and about 1.13 M dimmonium salt. The battery does not include an ion exchange membrane. One example of an electrolyte can be prepared in 5 M H2SO4 by adding 55 mL of concentrated sulfuric acid to 200 mL of deionized water, followed by adding 43.1001 g of MnSO4*H2O. The cell 100 includes a flow cell chamber 110. The chamber 110 is in contact with both a negative electrode 120, and a positive electrode 130. The negative electrode 120 and positive electrode 130 are connected to a power source or load 140. An electrolyte or anolyte/catholyte is pumped by a pump 150 from an electrolyte reservoir 160 through the first compartment 110. The catholyte passes through the porous negative electrode 120 and is collected in the reservoir 170. The anolyte passes through the porous positive electrode 130 and is collected in the reservoir 180.
U.S. Pat. No. 9,559,375 discloses an iron flow battery. The iron flow cell 100 includes two half cells 102, 104, separated by a separator 106. Half cells 102 and 104 include electrodes 108 and 110, respectively, in contact with an electrolyte. An anodic reaction occurs in half cell 104, and a cathodic reaction occurs in half cell 102, making the electrode 110 the negative electrode. The electrolyte in half cells 102, 104 flows through the system to storage tanks 112, 114, respectively, so that fresh/regenerated electrolyte flows from the storage tanks into the half cells. The electrodes 108, 110 can be connected to another device to either supply electrical energy, or to receive electrical energy in order to be recharged.
The catholyte can be any suitable salt including chloride, sulfate, nitrate salt, or a combination of two or more thereof. In one example, the catholyte is a solution of FeCl2 and FeCl3. Although the range of acceptable concentrations is listed as 0.01 M to about 5M, a concentration of each of about 1.0 M is preferred. The catholyte includes Fe3+ stabilizing liquid such as cyanide, sucrose, glycerol, Ethylene glycol, DMSO, SAT, acetate, oxalate, citrate, acetyl acetonate, fluoride, tartrate, malic acid, succinic acid, amino acids, or combinations thereof. The concentration of the stabilizing liquid can range from about 0.01 M to about 10 M, but is preferably about 1 M to about 5 M. The catholyte also includes a salt such as NaCl, KCl, NH4CL, LICL, and similar salts.
The anolyte is a solution of FeCl2 having a similar concentration to the above-described catholyte. The anolyte includes a hydrogen evolution suppressing additive such as boric acid, heavy metals, and organic materials suitable as surfactants and corrosion inhibitors. The concentration of boric acid can be from about 0.1 M to about 5 M, with about 1 M being preferred. At higher temperatures, higher concentrations of boric acid it may be utilized. Possible heavy metals include Pb, Bi, Mn, W, Cd, As, Sb, Sn, or combinations thereof. The heavy metal additive can have a concentration from about 0.0001 M to about 0.1 M, with about 0.01 M to about 0.025 M being preferred.
The negative electrode is a steel coil having an iron plating. The negative electrode can also be a slurry electrode or fluidized bed electrode. Suitable particles for use with in the slurry include carbon-based particles such is graphitic, iron particles iron coated particles, or a combination thereof.
US 2016/0020493 discloses in iron-sulfide-based battery and anode. The battery includes an anode having iron sulfide as the active material. The sulfur content is at least 5% by weight of the total of all iron and sulfur. The battery further includes a cathode and an alkaline electrolyte. Preferably, the sulfur content of the anode is more than 10% by weight, and no more than 70% by weight. More preferred ranges of 20 to 40% weight sulfur, or 36 weight percent (50% atomic) sulfur or also discussed. A binder is used to bind the iron sulfide particles together. Suitable binders include PTFF, PVDF, Polyaniline, Pyrrole, Polyethylene, and PMMA. Other binders include acrylic binders, acetyl triethyl citrate, diethyl phthalate, polyalkylene glycol. The binder is typically about 10 to 20% by weight as compared to the iron sulfide. Conductive particles such as carbon black, graphite, silver, gold, graphene, carbon nanotubes, and others can also be included within the anode.
The nature of the cathode is described as not critical to this battery. Any positive electrode with a suitable potential is claimed to be usable. Suitable electrodes include nickel hydroxide, air cathodes, manganese dioxide, cadmium, and others. Air cathodes can be a powder composite including carbon black, catalyst particles such is manganese oxide, and a hydrophobic polymeric binder.
The electrolyte is an alkaline component dissolved in water. The alkaline components is a hydroxide of an alkali metal such is lithium, potassium, sodium, or cesium hydroxide, or combinations thereof. Hey separator can be included between the cathode and anode. The separator should be poorest to allow for passage of the electrolyte, but to prevent the electrodes from short-circuiting. Examples include polycarbonate, polypropylene, polyolefin, or other separators
WO 2016/203388 discloses a process for the production of a functionalized graphene. The process involves the exfoliation of a graphite electrode for producing graphene sheets functionalized with one or more of biomolecules. The biomolecules or any organic substance or organic molecule having functional groups capable of binding to graphene, such as carbohydrates, lipids, protons including enzymes, nucleic acids, primary and secondary metabolites, or natural substances. Enzymes such as alkaline phosphatase or peptides such as GSH are preferred. At least the electrode acting as the anode is made of graphite. The electrode acting as the cathode may be made of metal such as platinum or gold, or may be made from graphite. A phosphate buffered saline is used is the electrolyte solution.
U.S. Pat. No. 4,814,241 discloses electrolytes for redox flow batteries. The electrolyte contains from 1 to 4 normal hydrochloric acid and at least 0.5 mole/liter of an active material. The electrolyte further containers from 0.1 to 4 normalities of an acid comprising an anion which does not inhibit the electrode reactions in addition to the hydrochloric acid. The electrolyte reduces the cell resistivity and improves the solubility of active materials. In all examples, the negative electrolyte is 1.0 mole/liter chromic chloride, and the positive electrode is 1.0 mole/liter ferrous chloride and 1.0 mole/liter of ferric chloride. In one example, hydrobromic acid was used. Sulfuric acid can also be used. The iron/chromium system can be replaced by systems consisting of Mn/Cr, Br2/Cr, and Cl2/Cr.
CN 102198957 discloses a method for preparing vanadyl sulfate for vanadium ion redux flow battery. The method includes diluting concentrated sulfuric acid into dilute sulfuric acid. Then vanadic anhydride is directly added into the dilute sulfuric acid while staring to obtain a vanadium sulfate solution. A reducing agent is selected from one or more of the flavanol compounds, anthocyanin compounds, flavanoids, flavanol compounds, phenolic acid compounds, and vitamin substances.
Producing an electrochemical cell capable of efficiently and effectively producing electricity in meaningful, useful quantities from materials that are typically available in off-grid locations has proven to be difficult. Accordingly, there is a need for such a cell.